This invention is concerned with a flow operable switch device.
It is designed for association with a conduit; and is connectible in an electric signal circuit. Its function is to signal the circuit when fluid of a predetermined volume is flowing through the conduit.
A feature of the switch device lies in the manner in which it is associated with the conduit and in the manner in which it is caused to be actuated to open and closed conditions.
It includes a reed switch which is adapted to be opened or closed accordingly as the flux of a magnet is brought into a zone where it will influence the contacts of the reed switch or is withdrawn from such zone. The magnet is adapted to be normally positioned in the zone of influence under the bias of a spring; and is adapted to be drawn from such zone by pressure of liquid flow through the conduit acting upon a cup attached by a cordline to the magnet.
A desirable advantage of the switch device of the present invention is that its switch elements and the magnet are located externally of, and are not subject to, the harmful effects of the liquid flowing in the conduit.
In accordance with the invention, there is provided a flow operable switch device comprising a housing, a reed switch mounted to the housing having magnetically attractible contacts, a magnet movable in an elongated bore of the housing into and out of a zone of effective magnetic flux influence upon the contacts of the switch, a spring biasing the magnet into the zone, a string connected to the magnet and projecting externally of the housing, and a pull element connected to the projecting end of the string adapted under a predetermined force applied to it in a direction away from the housing to draw the magnet out of said zone.